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Thick Disk vs. Copper--The Cold Truth About Heat

Given the recent enthusiasm over the very thick aluminum disk-base construction typified by Fissler and Paderno, as well as the heated hurling of opinions about how it outperforms straightgauge copper or aluminum constructions in terms of "specific heat", I thought I’d offer some hard numbers.

One of the javelins thrown in favor of the Fissler type (7mm-thick core) is that it “holds more heat” than a 2.5mm or 3mm copper pan with an otherwise identical geometry. This is heat capacity, not specific heat, and as Sam Kinsey writes, it's a function of volume and a number relative to water. This capacity, say the claimants, makes this disk construction a better choice where quantities of cold food are placed in the pan; the thick conductive disk allegedly has more heat to “give” the food in cooking.

But is this really true? Let’s compare two sauté pans of a common size, 11 inches (28cm) diameter by 3 inches (7.62cm) tall.

The area of such a 28cm circle is 615cm2. Although we know differently, we’ll charitably assume that the area of the Fissler’s aluminum core is also actually that area. Simple geometry then tells us that the volume of that 0.7cm core is 430.5cm3. Then physics informs us that with a specific heat per cubic centimeter of 2.42 J/cm3K, the aluminum core can “store” 1,043 Joules of heat energy. That’s quite a bit, and very useful for the stated purpose.

Now let’s consider a 2.5mm bimetal copper sauté of the same size. To be accurate, the actual thickness of copper in such a pan is only 2.3mm. However, because the copper extends up the walls, the area of the conductive material is greater, 1,285.56cm2 (615 for the base and another 670.56cm2 for the walls). The volume of copper in that 2.3mm construction pencils to 295.56cm3. When we apply the known specific heat per cubic centimeter of copper, namely 3.44 J/cm3K, (aka the volumetric heat capacity) we can see that the 2.3mm copper “stores” 1,017 Joules (A true 2.5mm pan would store 1,105J, and a 3.2mm extra fort sauté would hold 1,415J).

So, 1,043 versus 1,017 Joules? The spearchuckers are technically correct—the Fissler’s aluminum holds 2% more heat than does the copper in a 2.3mm bimetal sauté such as made by Falk or Bourgeat.But my Dehillerin 3.2mm sauté holds 26% *more*.

I encourage the Peanut Gallery to also try to calculate the heat stored in the Fissler’s SS walls (and the handles). But if/when they do, they should account for the fact that almost none of that heat will be conducted into the food or back to the disk in a saute. And they should also consider the differences in rebound (heat transfer *back into* the saute) between the two constructions.

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